WASHINGTON -- President Joe Biden on Monday proposed major changes for the U.S. Supreme Court: an enforceable code of ethics, term limits for justices and a constitutional amendment that would limit the justices’ recent decision on presidential immunity.

There’s almost no chance of the proposal passing a closely divided Congress with Election Day looming, but the ideas could still spark conversation with public confidence in the court hitting an all-time low amid ethical revelations about some justices. It also comes against the backdrop of a contentious presidential election and growing Democratic outrage about recent decisions from the conservative-majority court.

Here’s a look at how the ideas, how they might work, and the possible stumbling blocks:

How would justices’ terms be limited?

Limiting how long justices serve on the nation’s highest court has broad support among Americans, polling indicates.

A poll from The Associated Press-NORC Center for Public Affairs Research in July 2022 found 67 per cent of Americans support a proposal to set a specific number of years that justices serve instead of life terms, including 82 per cent of Democrats and 57 per cent of Republicans.

Biden’s proposal would limit justices to 18-year terms, a system that he says would make nominations more predictable, less arbitrary, and reduce the chances that a single president could shape the court for generations to come.

There’s a big problem: The Constitution gives all federal judges lifetime tenure, unless they resign, retire or are removed.

There are ideas about how to impose term limits without an amendment — but if such a law passed and were challenged in court the justices could end up ruling on it and it's unclear how they'd come down, said Charles Geyh, a law professor at Indiana University and expert in judicial ethics.

How would a code of ethics be enforced?

The Supreme Court didn't have a formal code of ethics until last year, when the justices adopted one in the face of sustained criticism over undisclosed trips and gifts from wealthy benefactors to some justices, like Clarence Thomas.

It still lacks a means of enforcement — something Biden says is “common sense.” Members of Congress, for example, generally can’t accept gifts worth more than US$50.

Anyone can file complaints against other federal judges, who are subject to censure and reprimand. Justice Elena Kagan voiced support for adding an enforcement mechanism to the Supreme Court ethical code in a public appearance last week.

Still, making the high court's ethical code enforceable raises thorny questions about how it might be enforced, and by whom.

Lower courts say their discipline process isn’t intended to directly police their code of ethics, maintaining the code is too broadly phrased for violations to directly translate into discipline, Geyh said.

That ethical code is overseen by the Judicial Conference, which is headed up by Chief Justice John Roberts. He “might be reluctant to use whatever power the conference has against his colleagues,” Stephen Gillers, a legal ethics expert at NYU School of Law, said in an email.

What about presidential immunity?

Biden is also calling for a constitutional amendment limiting the Supreme Court's recent decision giving former president Donald Trump — and all other presidents — broad immunity from criminal prosecution.

The amendment would “make clear that there is no immunity for crimes a former president committed while in office,” Biden wrote in an opinion piece in the Washington Post. “We are a nation of laws — not of kings or dictators.”

It wouldn't be the first time - the Constitution has been amended about five times to in US history to overturn a Supreme Court decision, Geyh said.

But constitutional amendments have even higher hurdles than new laws. The proposal must get support from two-thirds of both the House and Senate and then be ratified by three-quarters of state legislatures.

No new amendments have passed in more than 30 years. Republican House Speaker Mike Johnson has called Biden's proposal a “dangerous gambit” that would be “dead on arrival in the House.”

Biden has resisted other calls to reform the Supreme Court

A former chairman of the Senate Judiciary Committee, Biden has long resisted calls to reform the Supreme Court.

In 2021, he fulfilled a campaign promise by convening a commission to study potential changes to the court. It was not charged with making recommendations and cautioned that excessive change could potentially erode democracy.

The latest proposals come years later, and amid growing outrage among Democrats about high court opinions that overturned landmark decisions on abortion rights and federal regulatory powers. There's also a hotly contested presidential election against Trump underway.

Even if Biden's ideas aren't likely to pass, they could draw voter attention. Vice president Kamala Harris, who Biden endorsed for president after dropping out of the race, backed the proposal.

It's being blasted, though, by conservatives like activist Leonard Leo, who said in a statement: “It’s about Democrats destroying a court they don’t agree with."